1. Field of the Invention
The invention relates to the use of certain derivatives of .alpha.-methylstyrene as highly effective herbicides in the control of perennial grasses and sedges in the presence of such valuable crops as cotton, peanuts, potatoes and sugar beets.
2. Description of the Prior Art
It has long been realized that those perennial grasses which spread by the growth of underground stems represent an especially difficult problem in the matter of herbicidal control. Included in these weedy grasses that are especially troublesome to eradicate are purple nutsedge, yellow nutsedge, bermudagrass, orchardgrass, knotgrass and cogongrass (alang-alang). In general, herbicides used heretofore to treat the above-ground portions of such weeds have, at best, killed the above-ground portions of the weeds without at all eradicating the underground portions. Furthermore, mechanical treatments such as discing of these grassy weeds seems merely to result in cutting the underground stems into small portions, each of which tend to grow readily, resulting in a multiplication of the weeds rather than eradication.
It is therefore desirable to find a means for controlling and if possible eradicating refractory weed species such as those identified hereinabove.
The compounds of the present invention are embraced by the family of compounds the use of which is described in U.S. Pat. No. 3,373,011 issued Mar. 12, 1968. That patent describes the use of a number of substituted .alpha.-methylstyrene compounds in the control of grassy weeds. It is taught in the patent to use the substituted .alpha.-methylstyrenes for the control of small seeded grasses in preemergent applications as well as by discing into the soil around established crops. However, there is no teaching or suggestion in the said patent to employ the particular compounds of the invention by incorporating it into soil containing perennial grassy weeds whereby it is brought into a layer or band of soil above the underground stems of weeds classed as perennial sedges and grasses resulting in the highly effective control thereof in a manner not achieved by the use of any of the other of the substituted .alpha.-methylstyrenes described in the said patent.
The compounds of the present invention are also embraced by the family of compounds described in U.S. Pat. No. 3,391,203, issued July 2, 1968.